The present invention relates to the field of light display projectors and, more particularly, to a laser projector able to project within an increased viewing area.
There are various types of laser projectors being used in the field of laser light display. Currently known projectors generally include a laser, a color or intensity modulator, a number of beam deflecting actuators, a pair of galvanometric scanners, and a number of diffraction gratings for creating effects.
Present laser projection systems are used for generating abstract or vector graphic images by deflecting the laser beam from one of the beam deflecting actuators to the pair of galvanometric scanners which project an image on a projection surface. The resulting projection area which the galvanometric scanners are able to cover is dictated by the deflection angle capability of the scanners, which is generally about 60 degrees or less. This restricts the largest image that may be produced on a projection surface to a size about equal to the distance from the projector to the projection surface. One example of a projector which employs multiple pairs of galvanometric scanners is described by Tanaka in U.S. Pat. No. 5,130,838.
To produce an array of beams from a diffraction grating, one of the beam deflecting actuators directs the laser beam to a fixed diffraction grating. The light passing through or reflecting from the diffraction grating is directed into the air to produce an array of visible beams. The direction of this array of beams is determined by the fixed position of the diffraction grating, with the angle of the beams and the number of beams fixed by the type of diffraction grating being used.
These laser projectors can produce a static beam for beam pointing applications by directing the laser beam from one of the beam deflecting actuators onto a fixed mirror which then directs the laser beam to the desired target. However, in order to direct a static beam or diffraction grating effect toward a given target, movable mirror mounts must be adjusted with precision to reflect the laser beam. Usually, these adjustments must be made manually by an operator, and shortly before each presentation. The operator must necessarily work in very close proximity to the laser beam, creating the opportunity for the operator to be physically injured by direct exposure to the beam.
Prior art laser projectors are generally only able to perform one of these tasks at a time. For example, the projector may produce either a graphic image, a diffraction grating effect, or a static beam, but only one effect at a time using the full power of the laser. There is a need for a laser projector which can produce more than one of these effects simultaneously. In addition, prior art projectors are limited in their area of coverage due to their dependence on fixed components including galvanometric scanners, diffraction gratings, or reflecting mirrors. If a greater coverage area is desired, multiple components must be used for producing the various effects, for example, multiple pairs of galvanometric scanners for producing graphics in different locations, multiple fixed diffraction gratings for producing arrays of beams, and multiple reflecting mirrors fixed at various locations for producing aimed static beams. This adds to the cost, complexity, optical inefficiencies, and alignment difficulties encountered with prior art laser projectors. One example of a projector which employs multiple pairs of galvanometric scanners, multiple reflecting mirrors, and multiple gratings is that described by Slater et al. in U.S. Pat. No. 4,006,970.
Several systems have been devised in attempts to cover a greater area, particularly with graphic images. One known system uses a rotating reflecting mirror to cover an area up to 360xc2x0 in azimuth. However, this system uses a flat reflector, so that the area covered at one any one time is limited to the deflection angle of the galvanometric scanners. In addition, to address a new area the rotating reflecting mirror must be actuated by a motor. Because the mirror has a large mass, it takes a relatively long time for the motor to move the mirror to project toward a new area.
Another approach which is particularly well suited to domed projection surfaces is disclosed in U.S. Pat. No. 5,546,139 to Bacs et al. The Bacs projector uses a wide angle lens array to increase the deflection angle of the galvanometric scanners. Images created with this system can cover a 360xc2x0 azimuth by 180xc2x0 angle, which is normally oriented upward toward a dome. This system is expensive, decreases light throughput, and has a distinct focal length which results in increased beam divergence. In addition, manufacturing tolerances for the lenses are critical to ensure optimal lens performance, and any misalignment in the lens array or poor curvature in any one lens can cause chromatic aberration in the images.
With the foregoing in mind, the present invention advantageously provides a laser projector which projects graphic imagery covering an increased area, and an array of beam effects to be viewed 360xc2x0 in mid-air, both of which are easy to adjust and to target. The present laser projector is capable of simultaneously producing multiple visually perceptible images and effects directed toward different areas, while not requiring beam deflecting actuators, fixed diffraction gratings, fixed reflecting mirrors, or adjustable mirror mounts. The laser projector herein disclosed projects an array of beams which is visually perceived as a graphic image. The claimed laser projector does not require manual adjustment of components, and thereby does not expose an operator to potential injury due to accidental direct exposure to the laser beam.
The projector comprises a light source, preferably a laser, for producing an intense light beam, a color and intensity modulator for modulating the intensity and color of the light beam, a deflector for deflecting the light beam, and a projection reflector, which preferably includes a parabolic, spherical, hyperbolic or polyhedral reflector depending on the desired application. A focusing lens or lens array is positioned in the projector""s light path for producing a visually perceptible image having an improved focus and for reducing astigmatism. In addition, an optical fiber is preferably positioned connecting portions of the light path within the projector, such as between the light source and the deflector. Such use of an optical fiber, or fiber optic cable, allows the projector to be taken apart for transport, and joined back together for operation. In operation, this arrangement also permits one component of the projector to be spaced-apart from a second component, the light path between the two components formed by an optical fiber light conduit connecting the components. The projector can thus be made modular for certain installations which require portability or small component size.
The present projector is capable of replacing prior art light projectors since it can perform all of the tasks of these projectors while eliminating many components, with associated cost savings, increased reliability, and added safety. Additionally, the present laser projector will simultaneously produce multiple effects and visually perceptible images, directing these around 360xc2x0 and to about 40xc2x0 or more of elevation for viewing in mid-air or on a projection surface.